const Koa = require('koa')
const app = new Koa()

const one = (ctx,next) => {
console.log('<<one');
next()
console.log('one>>');
}

const two = (ctx,next) => {
    console.log('<<two');
    next()
    console.log('two>>');
    }
    
const three = (ctx,next) => {
    console.log('<<three');
     next()
    console.log('three>>');
    }
        

app.use(one)
app.use(two)
app.use(three)

app.listen(3000,() => {
    console.log('服务已启动');
})